1. Field of the Invention
The present general inventive concept relates to inkjet heads and methods of fabricating and replacing the same.
2. Description of the Related Art
Generally, an inkjet cartridge is a device for printing a predetermined image on a recording medium by ejecting ink droplets through an inkjet head.
FIG. 1 is a longitudinal cross-sectional view illustrating a configuration of a conventional inkjet cartridge 1.
Referring to FIG. 1, the inkjet cartridge 1 includes a cartridge body 11, a foam 13 inserted into the cartridge body 11 to retain ink, an ink supply unit 17 for supplying the ink from the foam 13 to a head 30, a filter 19 for filtering the ink when the ink is ejected from the ink supply unit 17, and a fluid-communicating hole 21 for facilitating the ink to come out of the foam 13 by providing communication between the cartridge body 11 and exterior air.
With this configuration, under the condition that the foam 13 having fine pores is pressurized and contained in the cartridge body 11, the cartridge body 11 is filled with a predetermined amount of ink. In this case, negative pressure is generated and maintained by a capillary phenomenon generated by the fine pores of the foam 13.
The head 30 may be classified into a thermal driving type and a piezo-electric driving type depending upon an ejection mechanism of an ink droplet. The thermal driving type generates bubbles in the ink by using a heat source and ejects the ink droplets by means of expansion of the bubbles, and the piezo-electric driving type ejects the ink droplets by means of pressure applied to the ink due to deformation of a piezoelectric material used therein.
FIG. 2 is a cross-sectional view illustrating a head structure of the prior art thermal driving type.
Referring to FIG. 2, a head 30 includes a substrate 31 having an ink supply hole 31a, a partition wall 37 installed on the substrate 31 to define an ink chamber 35 in which the ink is filled, a heat-generating body 39 installed in the ink chamber 35, and a nozzle plate 43 at which a nozzle hole 43a, through which the ink droplets are ejected, is formed. In this configuration, the ink supply hole 31a is in fluid communication with the ink supply unit 17 in FIG. 1.
In the head 30 configured above, first, when a pulse current is supplied into the heat-generating body 39 to generate heat therefrom, the ink 33 filled in the ink chamber 35 is heated to generate bubbles 45. As the generated bubbles are continuously expanded, the ink 33 filled in the ink chamber 35 is pressurized and ejected as ink droplets to an exterior through the nozzle hole 43a. Then, the ejection of the ink droplets is completed, and the bubbles are shrunk. When the bubbles are shrunk, the ink 33 is drawn back and refilled into the ink chamber. At this time, the shrinkage of the bubbles is caused by cooling of the heat-generating body 39 by switching off the pulse current.
Traditional inkjet printers, as shown in FIG. 1, have employed the inkjet cartridge traversing a width of a recording medium as a printing operation is performed.
However, recently, it becomes possible to manufacture a line type head, wherein the head extending throughout an entire width of the recording medium is fixedly maintained while the recording medium moves along the head.
FIG. 3 is a perspective view illustrating a configuration of an inkjet printer 100 to which a conventional line type head is adopted, disclosed in Japanese Patent Laid-open Publication No. 2001-301199, entitled “Inkjet Printer and Head Cartridge thereof.”
Referring to FIG. 3, the inkjet printer 100 includes a line head 120 (hereinafter, referred to as “inkjet cartridge”), a paper conveying unit 130, a paper feeder 140, a paper tray 150, and an electric circuit unit 160, which are contained in a housing 110. The housing 110 has a shape of a rectangular parallelepiped, provided with a paper discharging port 111 for discharging paper P on one side and a tray insertion port 112 for accessing the paper tray 150 on the other side. The inkjet cartridge 120 is provided with ink reservoirs of four colors consisting of cyan, magenta, yellow and black.
FIG. 4 is a longitudinal cross-sectional view of the inkjet cartridge 120 in FIG. 3.
Referring to FIG. 4, a head frame 121 is installed at a lower portion of the inkjet cartridge 120, being integrally formed with an ink tank 122 (hereinafter, referred to as “cartridge body”). The head frame 121 is formed thereon with a slit-type ink supply hole 123 and has a head 124 attached to both sides of the each ink supply hole 123.
The inkjet cartridge 1 or 120 as described above, and as shown in FIGS. 1 and 4, may be generally classified into two types: a disposable type where the head 30 or 124 is integrally formed with the cartridge bodies 11 and 122, and a head replacable type, while not shown, where the head is configured to be separated from the cartridge body.
For the former, the head 30 or 124 is connected to an ink supply system to fill the ink into a fluid channel of an inner portion thereof by a manufacturer.
However, for the latter, when the ink exists in the fluid channel of the inner portion of the head, leakage of the ink may be generated, thus making distribution of the products difficult, and causing an electrical failure. Therefore, in this case, the head is provided into the market without the ink in the fluid channel being in the inner portion of the head.
However, since an inner portion of the cartridge body has a negative pressure lower than an atmospheric pressure by virtue of a negative pressure generating means such as the foam 13, it is impossible for the ink in the cartridge body to be naturally introduced into the fluid channel of the head. Therefore, in the prior art, when the head is exchanged with a new one in the cartridge body, an auxiliary device, such as a suction apparatus, has been adopted in order to initially fill the ink. The suction apparatus includes a suction cap in contact with an outer surface of the head, and a suction pump connected to the suction cap through a tube. When a pumping force of the suction pump is allowed to provide a suction force to the suction cap, a predetermined quantity of the ink is forcedly discharged through a nozzle hole of a nozzle plate by the suction force.
When the suction apparatus is mounted in the printer and a user mounts a newly replaced inkjet cartridge on the printer, the suction apparatus is automatically operated by a maintenance program to introduce the ink stored in the cartridge body into the fluid channel in the head.
As described above, the conventional head exchangeable inkjet cartridge has a problem in that the suction apparatus is additionally required in order to introduce the ink in the fluid channel into the replaced head.
In addition, the conventional cartridge has a disadvantage of increasing loss of the ink as the suction operation is performed. Furthermore, a wide area of the head, like the line head type shown in FIGS. 3 and 4, increases the loss among of the ink.
In addition, in case of the line head type, the increase of the head area enhances possibility of generating a sealing leakage from the suction cap. In this case, the suction operation cannot be smoothly performed, so that the air remaining in the fluid channel in the head deteriorates the printing quality.